Intravascular diseases are commonly treated by relatively non-invasive techniques such as percutaneous translumenal angioplasty (PTA) and percutaneous translumenal coronary angioplasty (PTCA). These therapeutic techniques are well known in the art and typically involve the use of a balloon catheter and a guide wire, possibly in combination with other intravascular devices. The balloon catheter is advanced over the guide wire such that the distal end of the balloon catheter is positioned adjacent a restriction in a diseased vessel. The balloon is inflated and the restriction in the vessel is opened.
There are two basic types of balloon catheters used in combination with a guide wire: commonly referred to as over-the-wire (OTW) catheters and rapid-exchange catheters (RX). The construction and use of both OTW catheters and RX catheters are well known in the art.
A basic OTW catheter includes an inflatable balloon mounted on one end of a long shaft and a manifold connected to the other end. The manifold has two ports: a guide wire port and an inflation port. A guide wire is slidably inserted into the guide wire port, through the shaft and out the distal end of the balloon. The guide wire extends only a short distance outside either end of the balloon catheter. In addition, when in use, only a short section of the catheter and guide wire remain outside the body. Thus, to remove the catheter while leaving the guide wire in place and retaining control of the guide wire, the length of the guide wire must be increased by attaching an extension wire. The extended guide wire allows the catheter to be removed while leaving the guide wire in place inside the body. However, this is a tedious and time consuming task which may jeopardize the patient's health when time is of the essence.
By contrast, RX catheters do not require an extension wire to remove the catheter while leaving the guide wire in place. A basic RX catheter includes an inflatable balloon mounted on one end of a long shaft and a manifold connected to the other end. The manifold only includes an inflation port, not a guide wire port. The guide wire port on a RX catheter is located on the distal end of the shaft. A guide wire is slidably inserted into the guide wire port, through only a distal portion of the shaft and out the distal end of the balloon. The guide wire is exterior to the catheter along the entire length of the catheter proximal of the guide wire port, and is interior to the catheter distal of the guide wire port. When in use, the length of the guide wire interior to the catheter is shorter than the length of the guide wire outside the body. Thus, to remove the catheter while leaving the guide wire in place, the catheter is simply slid off the wire without the need for an extension wire. The RX catheter design can save valuable time.
While RX catheters have advantages over the OTW catheters, RX catheters have a significant disadvantage. In an OTW catheter, if a guide wire requires replacement while in use, the old guide wire is removed and a new guide wire is inserted into the guide wire port on the manifold. In a RX catheter, if a guide wire requires replacement while in use, the old guide wire can be removed but the new guide wire can't be inserted because the guide wire port is located on the distal end of the shaft which is inside the body. To insert a new guide wire into a RX catheter, the RX catheter must be removed to expose the guide wire port. Removing the balloon catheter is not desirable because vascular access may be difficult to regain. Thus, while the RX catheter design is generally preferable over the OTW catheter design for quick and easy catheter exchange, the OTW catheter design is generally preferable over the RX catheter design for quick and easy guide wire exchange.
In view of the advantages of each of these features, it is desirable to have a catheter that allows for both a quick and easy catheter exchange and a quick and easy guide wire exchange.